In conventional backstands for unwinding rolls of paper, which use a worm mechanism for moving the housings and chucks toward and away from each other, the chucks being moved away from each other in order to accept a roll of paper and being moved toward each other in order to rotatably hold that roll of paper, the worm nut is suspended downwardly from the housing and connected to the worm. Such worms are exposed and may be damaged by objects which are dropped and strike the worm. A guard cannot be placed on top of the worm because the guard would interfere with the movement of the worm nut and housing as they are moved back and forth by the rotation of the worm.